Prevention and healthy diet
How food protects our health
Cancer, dementia, diabetes: Eating a healthy diet can prevent numerous diseases. Yet many people still underestimate the importance of food for prevention. Helmholtz researchers provide arguments for a more conscious approach to our meals, and develop the first treatments against malnutrition.
Broccoli helps to fight against cancer, sauerkraut protects against ulcers, grapes alleviate neurodermatitis: If you believe the cooking and lifestyle magazines, our refrigerators have long resembled small pharmacies. Because some of the foods in them seem to be able to perform true medical miracles. Scientific evidence? Vague at best. At any rate, none of these so-called superfoods can cure widespread diseases: We cannot eat ourselves healthy.
But it's also true that our diet plays a role in determining which diseases we develop over the course of our lives. Excessive consumption of sugar, for example, threatens the dental health of even small children, excess cholesterol can double the risk of heart attack in young adults, and so-called junk food puts a strain on our bodies across all age groups. Meals made from fresh, carefully selected ingredients, on the other hand, prevent many diseases, as studies by Helmholtz researchers have repeatedly shown.
Low-salt meals, for example, strengthen our immune system, vegetarian food normalizes blood pressure. And those who eat a lot of vegetables and fish reduce their risk of developing Alzheimer's disease in the long term, according to a study by the German Center for Neurodegenerative Diseases, one of 18 Helmholtz centers. "This so-called Mediterranean diet seems to slow down certain degradation processes in the brain," explains the study's leader, neuropsychologist Michael Wagner. Together with his team, he examined the memory performance of around 500 test subjects with an average age of 70. The results showed that test subjects who preferred Mediterranean ingredients in their meals, such as fresh vegetables, legumes, fish and olive oil, were on average significantly less impaired than those who regularly consumed red meat, dairy products and saturated fats. There was also less evidence of impending impairments such as memory loss, agitation and disorientation, which are typical of Alzheimer's, in the cerebrospinal fluid of participants who appreciated Mediterranean cuisine. "Our food is not medicine," Wagner said, "but a conscious and sensible diet can prevent many diseases, not just dementia."
According to the expert, this prevention is particularly important in the case of Alzheimer's, because the disease develops gradually over many years and usually goes undetected at first. Certain protein deposits block the nerve cells and cause them to die, and at the same time the brain volume of those affected decreases. Why certain foods can slow down or even stop this damaging process has not yet been definitively researched, says Wagner. "We suspect that they dampen inflammatory processes in the brain and at the same time bind harmful metabolic products, the so-called free radicals, better."
However, current studies not only prove the positive effect of a balanced diet. The opposite, i.e., the consequences of one-sided meals, is also currently being researched. Mathias Heikenwälder is an expert on inflammation and cancer at the German Cancer Research Center (DKFZ) in Heidelberg. High-fat and high-sugar meals are considered an important risk factor for common diseases: One in four cases of cancer can be traced back to an unhealthy eating style, says the researcher.
He has investigated the harmful effect particularly intensively on the liver: If the organism takes in too much fat and sugar, it stores them; a survival mechanism of the body to be able to fall back on these depots in times of need. "In industrialized nations today, however, we live in a time of permanent oversupply, which is why these reserves are rarely called upon; instead, more and more people are developing obesity and what is known as a fatty liver," explains Heikenwälder. The organ then resembles the liver of alcoholics: It can no longer reliably perform the necessary metabolism and a chronic inflammation develops. In the worst case, cancer can even develop, because the T cells in the liver, normally important helpers of our immune system, lose their protective function and instead behave aggressively toward the tissue of the organ. A similar trend can be foreseen in emerging countries; more and more people are developing obesity and the resulting consequences.
One in three Germans suffers from a fatty liver, often without knowing it, the expert clarifies the dimension of the problem. "Many people nevertheless still underestimate the importance of nutrition for their health; even slight obesity triggers inflammatory processes in the body, which promote numerous diseases and can upset our hormonal balance." Heikenwälder emphasizes that it is easy to counteract this, especially through exercise and a diet rich in fiber, with plenty of fruit and vegetables, nuts and fish, and little meat. In order to spread the idea of prevention, massive educational campaigns are needed, especially in schools, says the scientist, but also stricter rules for the food industry.
Heikenwälder is now researching antibodies that could help to curb the damaging immune reactions in the liver. This is already succeeding in mice. Nevertheless, prevention through a healthy diet makes much more sense than hoping for a helpful drug, the cancer researcher emphasizes. Intermittent fasting, for example, has proven promising: Conscious, time-limited eating breaks help the metabolism to regain its balance. Heikenwälder studied the effect in mice suffering from fatty liver: If he gave the animals only water on two days per week, the fat levels in the liver dropped, even though the mice were able to eat as much as they wanted on the following day.
And intermittent fasting has been proven to help not only against fatty liver: The positive effects are also seen in numerous other diseases, such as high blood pressure and diabetes, cancer and obesity, explains Stephan Herzig, director of the Helmholtz Diabetes Center at Helmholtz Munich. He is investigating what exactly happens in the body during fasting: The metabolism does not shut down, after all, it must continue to supply the organism and especially the brain. But it does change radically, from burning sugar to burning fat.
Many people therefore lose weight through interval fasting. "But even in those who do not lose weight, we measure significantly improved values," Herzig emphasizes. In addition, this form of nutrition is quite uncomplicated compared to many other diets and therefore easy to follow through: There are only a few rules. Fasting takes place, for example, only on two days of the week or on each day over a period of 16 hours. In the remaining eight hours one may eat as much as they would like. Many fasting people forego breakfast, for example, but eat normally for the rest of the day. It is still better to omit the supper, says Herzig, in particular for humans with high blood sugar values. The reason for this is the human body's internal clock: In the morning, the insulin sensitivity of the body is high, food can be processed well. In the evening, the organism is less able to do this.
If diabetes patients undergo a fasting diet, their kidney function improves, the molecular biologist has found out: "So fasting helps not only preventively, but even therapeutically here."
Another positive aspect of interval fasting is that the very short phases of abstaining from food prevent people from getting used to it, which leads to the so-called yo-yo effect in many other diets: After a temporary weight loss humans quickly regain the lost Pounds; a frustrating experience. Many overweight people in particular are often accused of being too weak-willed to lose weight, observes Paul Pfluger of Helmholtz Munich. "A misconception!" This is because obesity, i.e., morbid obesity, is often also genetically determined. Pfluger estimates that in about 60 percent of those affected, their genes, combined with a poor lifestyle, play a decisive role. This makes it all the more important to find alternative ways of treating them, he says.
The Munich neurobiologist and diabetes expert Pfluger is therefore investigating the molecular processes responsible for the yo-yo effect and obesity. He discovered that communication in the brain is disturbed in many overweight people. Specifically, the satiety signal does not get through. Hormones such as leptin are responsible for this: It signals to the brain that the fat stores are full. But some people are resistant to leptin. They then feel excruciating hunger despite sufficient food intake.
Pfluger has discovered that a plant-based active ingredient from Chinese medicine could provide a remedy: Celastrol. This substance restores the brain's sensitivity to leptin, which could help patients regain their feeling of fullness. Tested on overweight mice, Celastrol has already shown promising results: The animals ate less and lost ten percent of their weight within just one week. Whether such effects can also be expected in humans is currently being investigated in the USA.
Pfluger himself is already pushing ahead with another idea for the treatment of severe obesity. He is focusing on special nerve cells in the brain that control our appetite, the so-called AgRP neurons. They seem to be permanently activated in obesity sufferers: This is one reason why those affected experience severe hunger attacks, even though they have an adequate supply of food. Pfluger is now investigating which gene sequence is responsible for the neurons' permanent alarm. "If we find it, we might be able to develop a treatment that turns off this element."
However, a miracle pill that allows unhealthy eating will not be available in the future, the metabolism expert emphasizes; a conscious eating style remains crucial. Here Pfluger also warns against extreme diets for the slightly overweight: They strengthen the feared yo-yo effect because they create so much panic in the body that for years afterwards it can remain in a savings mode, maintaining fat reserves as a precaution. If you want to prevent this mechanism, you should instead reduce your calorie intake in moderation, but over a longer period of time.
To ensure that the change in diet is successful, it is also important to set realistic goals, such as losing ten percent of one's weight within a year. Those who persevere with this are clearly doing their bodies some good, says Pfluger: "Blood lipid levels normalize, the risk of heart attacks decreases, and the risk of developing diabetes also falls."
In order to protect our health, both things help: The targeted selection of foods that have a preventive effect, as well as a conscious eating style that avoids an oversupply of stressful substances. If this change is successful, the effects are quickly apparent. When losing weight, for example, a minus of five percent of the body weight is already enough to begin with, Pfluger emphasizes. "And anyone can do that!"
- A balanced diet contributes significantly to maintaining our health and mental fitness. This preventive effect has been proven by numerous studies.
- The negative consequences of an unbalanced diet have also been proven: An excess of fat, sugar and salt weakens the immune system, strains the organs and can lead to numerous diseases such as diabetes, cancer and Alzheimer's.
- When people are overweight, dangerous inflammatory processes develop in the fat reserves that can damage the entire organism. If sufferers fail to lose weight in the long term, novel treatments and preventative measures could help in the future.
- Short-term periods of hunger are helpful for an optimally functioning metabolism: Intermittent fasting normalizes sugar and fat levels in the blood and also lowers blood pressure. Many people find this change in diet fairly easy, and at the same time there is a lesser risk of encountering the yoyo effect.